A long term evolution-advanced (referred to as “LTE-A”) system is a further evolution and enhancement system of a 3rd generation partnership project (referred to as “3GPP”) long term evolution (referred to as “LTE”) system. In the LTE-A system, in order to meet the requirements of International Telecommunication Union on the peak data rate of the fourth generation communication technology, carrier aggregation (referred to as “CA”) technology, also known as spectrum aggregation technology or bandwidth extension technology, is introduced. In carrier aggregation, the frequency spectrums of two or more component carriers are aggregated together to obtain a wider transmission bandwidth, and the frequency spectrums of the component carriers may be adjacent continuous frequency spectrums and may also be non-adjacent frequency spectrums in the same frequency band and even discontinuous frequency spectrums in different frequency bands; LTE Rel-8/9 user equipment (referred to as “UE”) may access only one component carrier to receive and send data, while the LTE-A user equipment may simultaneously access multiple component carriers according to the capacity and service demand thereof to receive and send data.
In any one of the existing carrier aggregation systems, only the carriers under the same base station are aggregated together. In a subsequent evolved LTE system, carrier aggregation between base stations will be introduced; at this time, non-ideal retransmission is performed between the base stations, and real-time data transmission could not be achieved between the base stations. A type of low-capacity user equipment may exist in the above-mentioned system of carrier aggregation between base stations, and the type of low-capacity user equipment could not simultaneously operate on carriers corresponding to multiple base stations, and may only operate on the carrier corresponding to one base station at each moment. Although high-capacity user equipment may operate in the above-mentioned system of multi-carrier aggregation between base stations, it may generate a wrong scheduling condition, since the data scheduling of multiple downlink carriers is independently performed by each base station.